Triangulation, measuring distances

Before a test is started, the coordinates of the flare and the radiometers (see Chapter 6) used to measure radiation are determined by utilizing a laser range finder to measure distances to three fixed objects with known coordinates and a technique called "triangulation." Multiple radiometers are used to measure various radiant fluxes simultaneously. A photo of the radiation measurement system is shown in Figure 28.12. The measured radiant fluxes, through sophisticated mathematical analysis, are used to determine the coordinates of the effective "epicenter(s)" of the flame, and the radiant fraction, which is defined as the fraction of heat release from combustion that is emitted as thermal radiation [43]. Solar radiation is subtracted from the radiation measurements as appropriate. 

R. Dorsch, G. Hausler, and J. Herrmaim, Laser Triangulation Fundamental Uncertainty in Distance Measurement, Applied Optics, Vol. 33, No. 7 (1994). 

Another important approach has been to isolate ribosomal proteins from bacteria grown in D2O and then to reconstitute ribosomal subunits with pairs of deuterated proteins. By studying neutron scattering the distances between the centers of mass of these pairs could be measured. By triangulation the three-dimensional relationship of the entire group of proteins could be determined. The results of such studies for the SOS subunit are shown in Fig. 

Rqi2 will be dominated by A. Only when A is small can reliable information on be obtained. In summary, Rq data on subunit shapes as well as the distances A can be derived by triangulation methods, although four additional measurements of interference functions are now necessary beyond the minimum required for simple triangulation [481]. 

The transponders reply, and the replies are received again by either the ship or the seabed device (1). Signal runtime measurements can now determine the distances 1-2,1-3, and 1-4, which are used to compute the ship or device position by triangulation or position search algorithms. These transponders are generally deployed around the perimeter of a work site. This technique results in a high positioning accuracy (few centimeters to 1 m) that is independent of water depth (Anderson, 1985). 

Electronic sensors for direction and distance measurements and more powerful and cheaper computers opened the way to new applications for electronic theodolites and tacheometers. 3D-measurement systems were developed for surveying of industrial objects using triangulation, trilateration, or polar measurement methods. 

For a long time geodesists have been very well versed in handling networks. In almost all countries the ordnance survey is based on a triangulation network. Between the points of a geodetic network directions and distances are measured or the points are used for a photogrammetric analysis (Gaufi 1887 Linkwitz 1961 Baarda 1968). 

The temperature increase during operation of the scanner (light source, internal processor) may alter the measurement due to variation of distance between the transmitter and the CCD sensor affecting the triangulation process. 

The deflection is measured by using a laser triangulation and parallax method. The laser sensors are responsible for measuring the distance to the pavement surface, and the deflection is calculated from the difference between the slope of the beam and the slope of the pavement at the initial point and after the device moves to the next point. The device is provided with a data acquisition system used for data collection, storage and analysis (Elseifi et al. 2012). 

Laser triangulation method is a technique which uses the law of sine to find the coordinates and distance of an unknown point by forming a triangle with it and two known reference points [2]. In Fig. 12.8, A and B are the two reference locations given by the camera and the sensor locations, and C is the location of the object point of interest. The distance from A to B can be measured as c, and the angles a and P can also be measured. Following the law of sine the distances a and b can be calculated. The coordinates of A and B are known, then the coordinate of C can also be calculated. The same principle is employed in various other scaiming methods. 

Inter-void distances (IDs) were measured according to the procedure discussed above and an example for connected lines and those affected by the edges of triangulation network is given in Figure 3.13. 

Figure 3.13. An example of triangulation for inter-void distance measurement (a) after removing lines affected by edge effect , where white dotted lines are affected by the edges when the middle section of black dashed line is taken as an image for measurement and (b) image taken from (a) where black lines along the edges of image are fictitious as compared with white dotted line in (a) [51]...

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